Magnetoresistance of the organic superconductor bis-tetramethyltetraselenafulvalenium perchlorate [(TMTSF)2ClO4]: Kohler's rule

Abstract

We report a study of the magnetoresistance of the organic superconductor bis-tetramethyl-tetraselenafulvalenium perchlorate [${\mathrm{}\left(\mathrm{TMTSF}\right)\mathrm{}}_2$Cl${\mathrm{O}}_4$] from 1.8 to 20 K in fields up to 79 kG, for current flow both parallel and perpendicular (${\overrightarrow{\mathrm{c}}}^{*}$) to the highly conducting $\overrightarrow{\mathrm{a}}$ axis. For the latter, Kohler's rule is obeyed and the results can be understood in terms of standard theory for an open Fermi surface. We argue that $\overrightarrow{\mathrm{a}}$ is not exactly a principal axis of the conductivity tensor. Then the field dependence of the longitudinal conductivity can be understood within the same picture. For slowly cooled samples there are deviations from Kohler's rule which can be attributed to magnetic breakdown of superlattice gaps.